A facile and mild synthesis of 1-D ZnO, CuO, and α-Fe₂O₃ nanostructures and nanostructured arrays

ZnO nanowires, CuO nanowires, and α-Fe₂O₃ nanotubes as well as their corresponding arrays have been successfully synthesized via a low cost, generalizable, and simplistic template method. Diameters of one-dimensional (1-D) metal oxide nanostructures (∼60-260 nm), measuring micrometers in length, can be reliably and reproducibly controlled by the template pore channel dimensions. Associated vertically aligned arrays have been attached to the surfaces of a number of geometrically significant substrates, such as curved plastic and glass rod motifs. The methodology reported herein relies on the initial formation of an insoluble metal hydroxide precursor, initially resulting from the reaction of the corresponding metal solution and sodium hydroxide, and its subsequent transformation under mild conditions into the desired metal oxide nanostructures. Size- and shape-dependent optical, magnetic, and catalytic properties of as-prepared 1-D metal oxides were investigated and noted to be mainly comparable to or better than the associated properties of the corresponding bulk oxides. A plausible mechanism for as-observed wire and tube-like motifs is also discussed.